Offshore drilling rigs often include direct-acting tensioners to compensate for wave-induced motion. More specifically, the direct-acting tensioners may include one or more massive hydraulic cylinders having a piston rod. The hydraulic cylinders continuously dampen wave-induced motion and thereby balance the drilling rig and/or stabilize the drill string. As such, dampening may be optimized by measuring, monitoring, and adjusting a position of the piston rod within the hydraulic cylinder. Moreover, the hydraulic cylinders are generally mounted below a deck of the drilling rig, i.e., in a splash zone, and are therefore often exposed to an extremely corrosive and wear-inducing environment from airborne salt spray, sea water, ice, moving cables, and/or debris. Consequently, the piston rods of such hydraulic cylinders must exhibit excellent corrosion-resistance and wear-resistance, and must remain crack-free over a service life.
Other types of piston rods and hydraulic cylinders may actuate large gate valves for applications including canals, locks, hydrodynamic power plants, foundries, and metal processing facilities. Actuation of the gate valves may be controlled by measuring and adjusting a position or displacement of the piston rods within the hydraulic cylinders. Further, the piston rods may undergo thousands of wear-inducing displacements and/or may experience impacts from moving machinery, components, and seals during operation of the hydraulic cylinders.